Gonzales will be the first witness Feb. 6 in a planned series of hearings by the committee.
"I have no interest in surprising the attorney general," Specter said in an interview. "I have a keen interest in having him be prepared to answer these questions. These are serious . . . deep, profound matters."
The senator said the disclosure of the administration's ongoing surveillance since 2001 has complicated negotiations over the reauthorization of the USA Patriot Act.
"It also complicated the Alito hearings," Specter said of the committee's just-concluded confirmation hearings for Supreme Court nominee Samuel A. Alito Jr.
During the committee vote Tuesday on Alito's nomination, a senior Republican expressed concern about the surveillance program.
"I am very concerned that the war resolution [of 2001] is being interpreted overly broad," said Sen. Lindsey Graham (R., S.C.).
In a speech Tuesday at Georgetown University's Law School, Gonzales defended the program, which allows the National Security Agency to intercept calls to and from the United States without warrants.
Gonzales argued that the requirements of a secret intelligence court, created by the Foreign Intelligence Surveillance Act of 1978, were too burdensome to allow for rapid tracking of suspected terrorists.
The White House contends that authorization is implicit in a congressional resolution approved Sept. 14, 2001. Specter asked in his letter why the administration did not seek authorization for wiretapping in the subsequent passage of the Patriot Act.
Specter also asked whether, in signing the 1978 act establishing the court, President Carter was giving up inherent authority to conduct warrantless domestic surveillance.
"It's conceivable" that Carter would be asked to testify, Specter said. "I'm thinking about asking the elder Bush, to have balance."
Former President Gerald Ford, who was released from the hospital yesterday after being treated for pneumonia, might not be well enough to appear.
Gonzales will also be asked if he would consider "seeking approval from the FISA Court at this time for the ongoing surveillance program," according to the letter.
"I don't know if it [the approval] would be granted, but why not ask?" Specter said. "There would be a lot of reassurance about the legality of the program if you had that kind of oversight."
Specter also contended that the administration was required to notify not just congressional leaders but the intelligence committees as well about the existence of the surveillance program.
Contact staff writer Steve Goldstein at 202-383-6048 or email@example.com.